Use of sterol esters as an additive in asphalt binder

Abstract

Disclosed are asphalt and asphalt binders and methods for making such compositions with sterol esters. The sterol esters improve various rheological properties of the asphalt and asphalt binders. Also disclosed are methods of determining the changes or improvements of various rheological properties.

Description

USE OF STEROL ESTERS AS AN ADDITIVE IN ASPHALT BINDERCross-Reference to Related Applications

[0001] This application claims the benefit of U.S. Provisional Application Nos. 63 / 527,188 filed July 17, 2023, incorporated herein by reference in its entirety.Background

[0002] Asphalt pavement is one of the most recycled materials in the world, finding uses in shoulders of paved surfaces and bridge abutments, as a gravel substitute on unpaved roads, and as a replacement for virgin aggregate and binder in new asphalt pavement. Typically, use of recycled asphalt pavement is limited to sub-surface pavement layers or to controlled amounts in asphalt base and surface layers. Such uses are limited in part because asphalt deteriorates with time, loses its flexibility, becomes oxidized and brittle, and tends to crack, particularly under stress or at low temperatures. These effects are primarily due to aging of the organic components of the asphalt, e.g., the bitumen-containing binder, upon exposure to environmental factors. The aged binder is also highly viscous. Consequently, reclaimed asphalt pavement has different properties than virgin asphalt and is difficult to process.

[0003] To reduce or retard the impact of asphalt aging on the long-range performance of mixtures, numerous materials have been investigated. For example, rejuvenators are marketed with a stated goal of reversing the aging that has taken place in recycled raw materials such as reclaimed asphalt pavement (RAP) and reclaimed asphalt shingles (RAS). ft is unlikely that the marketed rejuvenators actually rejuvenate asphalt and the more likely scenario is that these additives may instead serve as softening agents for the virgin binders employed in mixtures containing RAP or RAS or combinations of both. In some instances, 10% or more by weight of these softening agents are added to the virgin binder when such mixtures are produced. As a result, the entire blend of virgin binder, rejuvenating additive and recycled binder additive has reduced stiffness versus the same blend without the rejuvenating additive.Summary

[0004] Disclosed are compositions and methods that may retard, reduce or otherwise overcome the effects of aging in recycled or reclaimed aged asphalt so as to preserve or retain some or all of the original properties of the virgin binder or virgin asphalt originally used when laying down the aged asphalt. In some embodiments, the disclosed compositions and methods may alter the aging rate of the total binder present in a mix containing virgin asphalt and high levels of RAP or RAS. Thedisclosed compositions and methods use a class of plant derived chemistry, the sterol esters group of compounds like those depicted in Figure 1. While plant sterol esters do not contain the same number of condensed or partially unsaturated rings as asphaltenes, they do have the benefit of not being a linear or branched linear molecule.

[0005] In one embodiment, the present disclosure provides a method for slowing the aging or restoring aged asphalt binder comprising adding a sterol to an asphalt binder, wherein the asphalt binder comprises a virgin asphalt binder, reclaimed asphalt binder material comprising asphalt pavement (RAP), asphalt shingles (RAS) or combinations of both and from 0.5 to 15 wt. % of the sterol ester source based on the virgin asphalt binder

[0006] In one embodiment, the present disclosure provides a method for reusing reclaimed asphalt binder for asphalt pavement production, comprising adding a sterol ester to an asphalt binder, wherein the asphalt binder comprises a virgin asphalt binder, reclaimed asphalt binder material comprising asphalt pavement (RAP), asphalt shingles (RAS) or combinations of both and from 0.5 to 15 wt. % of the sterol based on the virgin asphalt binder.

[0007] In another embodiment, the present disclosure provides an asphalt comprising, virgin asphalt binder, reclaimed asphalt binder material comprising reclaimed asphalt pavement (RAP), reclaimed asphalt shingles (RAS) or combinations of both, and a sterol ester, wherein from 0.5 to 15 wt. % of the sterol ester source is based on the virgin asphalt binder.

[0008] In yet another embodiment, the present disclosure provides method for restoring aged asphalt binder comprising adding a sterol and virgin asphalt binder to a reclaimed asphalt binder, wherein 0.5 to 15 wt. % of the sterol ester is based on virgin asphalt binder.

[0009] In one embodiment, the present disclosure provides an asphalt or binder comprising virgin asphalt binder, reclaimed asphalt binder material comprising reclaimed asphalt pavement (RAP), reclaimed asphalt shingles (RAS) or combinations of both, and an anti-aging additive in the range of 0.5 to 15 wt. % of the virgin binder, wherein the anti-aging additive contains sterol esters or ester blends.

[0010] In one embodiment, the present disclosure provides an asphalt or binder comprising virgin asphalt binder, reclaimed asphalt binder material comprising reclaimed asphalt pavement (RAP), reclaimed asphalt shingles (RAS) or combinations of both, and a restorative additive in the range of 0.5 to 15 wt. % of the virgin binder, wherein the restorative additive contains sterol esters or ester blends.

[0011] In another embodiment, the present disclosure provides a method for slowing the aging or restoring aged asphalt or binder comprising: adding an anti-aging additive to an asphalt binder, wherein the asphalt binder comprises a binder, reclaimed asphalt binder material comprisingreclaimed asphalt pavement (RAP), reclaimed asphalt shingles (RAS) or combinations of both, wherein the anti-aging additive is added in a range of 0.5 to 15 wt. % of the virgin asphalt binder.

[0012] Exemplary embodiments of the present disclosure include, for example, i) asphalt binder comprising RAS at a binder replacement level 1% and greater, ii) asphalt binder comprising RAP at binder replacement levels 20% and greater, iii) asphalt binder comprising RAP and RAS used in combination at binder replacement levels of 10% and greater RAP-derived binder and binder replacement levels of 1% and greater RAS-derived binder, iv) asphalt binder comprising asphalt binder extracted and recovered from post-consumer waste shingles at binder replacement levels of 3% by weight and greater, v) asphalt binder comprising asphalt binder extracted from manufacture’s waste shingles at binder replacement levels of 5% by weight and greater, vi) asphalt binder comprising oxidized asphalts meeting ASTM specification D312 for Type II, Type III, or Type IV and coating asphalt at binder replacement levels of 3% by weight and greater, vii) asphalt binder comprising extracted and recovered RAP at binder replacement levels of 10% by weight and greater, viii) asphalt binder comprising re-refined engine oil bottoms (REOB) at binder replacement levels of 1% and grater by weight, ix) asphalt binder comprising paraffinic oils at binder replacement levels of 1 % and greater by weight, x) asphalt paving comprising aggregate, aggregate and RAP, aggregate and RAS, or aggregate and a combination of RAP and RAS mixed with binder containing REOB at binder replacement levels of 1% and higher by weight; xi) said asphalt pavings as enumerated in x) mixed with paraffinic oils at binder replacement levels of 1 % and higher by weight.

[0013] Other embodiments comprise a method for applying a road pavement surface, which method employs an asphalt comprising aggregate, virgin asphalt binder, reclaimed asphalt material comprising RAP, RAS or combinations of both, a sterol ester, and a softening agent, wherein the sterol ester content is at least about 0.5 wt.%, at least about 1 wt. %, or up to about 10 wt.%, or up to about 15 wt. % based on the virgin asphalt binder weight. In a further embodiment, the asphalt paving is prepared, mixed, applied to a base surface, and compacted.Brief Description of Drawings

[0014] FIGURE 1 depicts structures of four representative plant sterols useful in the practice of this disclosure, specifically beta-sitosterol, campesterol, stigmasterol, and sitostanol.

[0015] FIGURE 2 is a graph demonstrating characteristics of the present anti-aging additives, as discussed in the Examples below.

[0016] FIGURE 3 is a graph demonstrating characteristics of the present anti-aging additives, as discussed in the Examples below.

[0017] FIGURE 4 is a graph demonstrating characteristics of the present anti-aging additives, as discussed in the Examples below.

[0018] FIGURE 5 is a graph demonstrating characteristics of the present anti-aging additives, as discussed in the Examples below.

[0019] FIGURE 6 is a graph demonstrating characteristics of the present anti-aging additives, as discussed in the Examples below.

[0020] FIGURE 7 is a graph demonstrating characteristics of the present anti-aging additives, as discussed in the Examples below.

[0021] FIGURE 8 is a graph demonstrating characteristics of the present anti-aging additives, as discussed in the Examples below.

[0022] FIGURE 9 is a graph demonstrating characteristics of the present anti-aging additives, as discussed in the Examples below.

[0023] FIGURE 10 is a graph demonstrating characteristics of the present anti-aging additives, as discussed in the Examples below.

[0024] FIGURE 11 is a graph demonstrating characteristics of the present anti-aging additives, as discussed in the Examples below.

[0025] FIGURE 12 is a graph demonstrating characteristics of the present anti-aging additives, as discussed in the Examples below.Detailed Description

[0026] The disclosed asphalt contains anti-aging (viz., age reducing or aging retarding) additives that help in the preservation, recycling and reuse of asphalt or asphalt binder. The disclosed compositions have particular value for the renewal of reclaimed asphalt, and especially RAP.

[0027] The disclosed asphalt compositions provide for recycled asphalt (e.g., RAP or RAS) the binders of which may have improved physical and rheological characteristics such as stiffness, effective temperature range, and low temperature properties compared to binders that do not contain the disclosed additives. Some embodiments provide for the use of binder extracted from RAS in asphalt blends. Certain embodiments provide for the addition of an additive to minimize potential detrimental low-temperature effects of recycled asphalt while allowing for higher stiffness at high temperatures.

[0028] Headings are provided herein solely for ease of reading and should not be interpreted as limiting.Abbreviations, Acronyms & Definitions

[0029] “Aged” refers to asphalt or binder that is present in or is recovered from reclaimed asphalt. Aged binder has high viscosity compared with that of virgin asphalt or virgin binder as a result ofaging and exposure to outdoor weather. The term “aged” also refers to virgin asphalt or virgin binder that has been aged using the laboratory aging test methods described herein (e.g. RTFO and PAV). “Aged” may also refer to hard, poor-quality, or out-of-specification virgin asphalt or virgin binder particularly virgin binders having a ring-and-ball softening point greater than 65°C by EN 1427 and a penetration value at 25°C by EN 1426 less than or equal to 12 dmm.

[0030] “Aggregate” and “construction aggregate” refer to particulate mineral material such as limestone, granite, trap rock, gravel, crushed gravel, sand, crushed stone, crushed rock and slag useful in paving and pavement applications.

[0031] “Anti-aging additive” refers to sterol esters or sterol ester mixtures that can be combined with aged binder to retard the rate of aging of asphalt or binder, or to restore or renew the aged asphalt or aged binder to provide some or all of the original properties of virgin asphalt or virgin binder.

[0032] “Asphalt” refers to a binder and aggregate and optionally other components that are suitable for mixing with aggregate and binder. Depending on local usage, the terms “asphalt mix” or “mix” may be used interchangeably with the term “asphalt.”

[0033] “Asphalt pavement” refers to compacted asphalt.

[0034] “Binder” refers to a highly viscous liquid or semi-solid form of petroleum. “Binder” can include, for example bitumen. The term “asphalt binder” is used interchangeably with the term “binder.”

[0035] ‘ ‘Bitumen” refers to a class of black or dark-colored (solid, semisolid, or viscous) cementitious substances, natural or manufactured, composed principally of high molecular weight hydrocarbons, of which asphalts, tars, pitches, and asphaltenes are typical.

[0036] “Crude” when used with respect to a material containing a sterol means sterol that has not been fully refined and can contain components in addition to sterol.

[0037] “M-critical” or “Creep critical” grade refers to the low temperature relaxation grade of a binder. The creep critical temperature is the temperature at which the slope of the flexural creep stiffness versus creep time according to ASTM D6648 has an absolute value of 0.300.Alternatively, the stiffness and creep critical temperatures can be determined from a 4 mm Dynamic Shear Rheometer (DSR) test or Bending Beam Rheometer (BBR).

[0038] “Neat” or “Virgin” binders are binders not yet used in or recycled from asphalt pavement or asphalt shingles, and can include Performance Grade binders.

[0039] PAV” refers to a Pressurized Aging Vessel. The PAV is used to simulate accelerated aging of asphalt or binder as described in ASTM D6521-13, Standard Practice for Accelerated Aging of Asphalt Binder Using a Pressurized Aging Vessel (PAV).

[0040] “Pure” when used with respect to a sterol ester or mixture of sterol esters means having at least a technical grade of purity or at least a reagent grade of purity.

[0041] “Reclaimed asphalt” and “recycled asphalt” refer to RAP, RAS, and reclaimed binder from old pavements, shingle manufacturing scrap, roofing felt, and other products or applications.

[0042] “Reclaimed asphalt pavement” and “RAP” refer to asphalt that has been removed or excavated from a previously used road or pavement or other similar structure, and processed for reuse by any of a variety of well-known methods, including milling, ripping, breaking, crushing, or pulverizing.

[0043] “Reclaimed asphalt shingles” and “RAS” refer to shingles from sources including roof tear- off, manufacture’s waste asphalt shingles and post-consumer waste.

[0044] “RTFO” refers to a Rolling Thin Film Oven. The RFTO is used for simulating the shortterm aging of binders as described in ASTM D2872-12el, Standard Test Method for Effect of Heat and Air on a Moving Film of Asphalt (Rolling Thin-Film Oven Test).

[0045] “S -Critical” or “stiffness critical” grade refers to the low temperature stiffness grade of a binder. The stiffness critical temperature is the temperature at which a binder tested according to ASTM D6648 has a flexural creep stiffness value of 300 MPa or as determined by either the Bending Beam Rheometer test or 4 mm DSR test as described in ATc.

[0046] SHRP refers to the Strategic Highway Research Program which develops new binder specifications in 1993.

[0047] “Softening agent” refers to low viscosity additives that eases (or facilitates) the mixing and incorporation of a recycled binder into virgin binder during an asphalt production process.

[0048] “Temp” is used in Tables and Figures as a contraction for the word Temperature.

[0049] “ATc” refers to the value obtained when the low temperature creep or m-value critical temperature is subtracted from the low temperature stiffness critical temperature. The 4 mm dynamic shear rheometer (DSR) test and analysis procedures are described by Sui, C., Farrar, M., Tuminello, W., Turner, T., A New Technique for Measuring low-temperature Properties of Asphalt Binders with Small Amounts of Material, Transportation Research Record: No 1681, TRB 2010. See also Sui, C., Farrar, M. J., Harnsberger, P. M., Tuminello, W.H., Turner, T. F., New Low Temperature Performance Grading Method Using 4 mm Parallel Plates on a Dynamic Shear Rheometer. TRB Preprint CD, 2011, and by Farrar, M., et al, (2012), Thin Film Oxidative Aging and Low Temperature Performance Grading Using Small Plate Dynamic Shear Rheometry: An Alternative to Standard RTFO, PAV and BBr. Eurasphalt & Eurobitume 5th E&E Congress-2012 Istanbul (pp. Paper O5ee-467). Istanbul: Foundation Euraspalt.

[0050] All weights, parts and percentages are based on weight unless otherwise specified.Binders

[0051] Current bituminous paving practices involve the use of high percentages of Reclaimed Asphalt Pavement (RAP) and Reclaimed Asphalt Shingles (RAS) as components in the bituminous mixtures being paved. Typically RAP concentrations can be as high as 50% and RAS concentrations can be as high as 6% by weight of the paving mixture. The typical bitumen content of RAP is in the range of 5-6% by weight and the typical bitumen content of RAS is in the range of 20-25% by weight. Consequently, a bituminous mixture containing 50% by weight of RAP will contain 2.5% to 3% RAP bitumen contributed to the final bituminous mixture and a bituminous mixture containing 6% RAS by weight will contain 1.2% to 1.5% RAS bitumen contributed to the final bituminous mixture. In many instances both RAP and RAS recycled additives are combined in a bituminous mixture; for example, 20% to 30% RAP and 5% to 6% RAS may be incorporated into a bituminous mixture. Based on the typical bitumen contents of RAP and RAS, bituminous mixtures containing 20% to 30% RAP and 5% to 6% RAS can result in 2% to as much as 3.3% binder (based on the total mixture weight) being derived from the RAP and RAS combination.Since a typical bituminous paving mixture will contain about 5.5% total bitumen, there accordingly may be about 36% to as much as 60% of the total bitumen in the bituminous mixture from these recycled sources.

[0052] Characteristics of bitumen in these reclaimed sources relative to virgin binders used in bituminous mixtures are shown in Table 1.Table 1

[0053] Table 2 shows the high and low temperature properties of samples produced with virgin binders and bitumen recovered from post-consumer waste shingles after different periods of aging. Also shown in Table 2 are high and low temperature properties of mixtures containing RAP and RAS. Some of these mixtures have undergone extended laboratory aging and some are from field cores.Table 2

[0054] Tables 1 and 2 show the impact of incorporating high binder replacement levels of recycled materials, especially those derived from post-consumer waste shingles. The data demonstrate the desirability of incorporating additives into bitumen and bituminous mixtures to mitigate the impact of the bitumen from these recycled components and retard further oxidative aging of the total bitumen in the final mixture. The last three rows of Table 2 show that the further away from the airmixture interface, the lower the impact on ATc parameter. This parameter may be used to assess the impact of aging on binder properties and more specifically the impact of aging on the relaxation properties of the binder; the relaxation property is characterized by the property referred to as “low temperature creep grade”.

[0055] Research published in 2011 showed, based on recovered binder data from field cores, that ATc could be used to identify when a pavement reached a point where there was a danger of non-load related mixture cracking and also when potential failure limit had been reached. In that research the authors subtracted the stiffness-critical temperature from the creep or m-critical temperature and therefore binders with poor performance properties had calculated ATc values that were positive. Since 2011 industry researchers have agreed to reverse the order of subtraction and therefore when the m-critical temperature is subtracted from the stiffness critical temperature binders exhibiting poor performance properties calculate to ATc values that are negative. The industry generally agreed that to have poor performing binders become more negative as performance decreased seemed to be more intuitive. Therefore, today in the industry and as used in the application, a ATc warning limit value is -3 °C and a potential failure value is -5 °C.

[0056] Reports at two Federal Highway Administration Expert Task Group meetings have shown a correlation between ATc values of binders recovered from field test projects and severity of pavement distress related to fatigue cracking. Additionally, it has been shown that when binders used to construct these field test projects were subjected to 40 hours of PAV aging, the ATc values showed a correlation to pavement distress related to fatigue cracking, especially top-down fatigue cracking which is generally considered to result from loss of binder relaxation at the bituminous mixture surface.

[0057] It is therefore desirable to obtain bituminous mixtures with bitumen materials that have a reduced susceptibility to the development of excessively negative ATc values.

[0058] The data in Table 1 show typical virgin binders produced at refineries can maintain a ATc of greater than -3°C after 40 hours of PAV aging. Further, the data in Table 1 show that binder recovered from RAP can have ATc values of less than -4°C, and that the impact of high RAP levels in new bituminous mixtures should be evaluated. Further, the extremely negative values of ATc for RAS recovered binders require additional scrutiny as to the overall impact of RAS incorporation into bituminous mixtures.

[0059] Table 2 shows that it is possible to age bituminous mixtures under laboratory aging followed by recovery of the binder from the mixtures and determination of the recovered binder ATc. The long-term aging protocol for bituminous mixtures in AASHTO R30 specifies compacted mix aging for five days at 85°C. Some research studies have extended the aging time to ten days to investigate the impact of more severe aging. Recently, aging loose bituminous mixes at 135°C for 12 and 24 hours and in some instances for even greater time periods have been presented as alternatives to compacted mix aging. The goal of these aging protocols is to produce rapid binder aging similar to field aging representative of more than five years in service and more desirably eight to 10 years in service. For example, it has been shown for mixtures in service for around eight years that the ATcof the reclaimed or recycled asphalt from the top * / 2inch of pavement was more severe than 12 hours aging at 135°C but less severe than 24 hours aging at 135°C.

[0060] The data in the first two rows of Table 2 show why long-term aging of mixtures containing recycled products is important. The binder recovered from the unaged mix (row 1) exhibited a ATc of -1.7°C, whereas the binder recovered from the 5-day aged mix exhibited a ATc of -4.6°C.Anti-Aging Additives

[0061] The disclosed additives may alter (e.g., reduce or retard) an asphalt binder aging rate, or can restore or renew an aged or recycled binder to provide some or all of the properties of a virgin asphalt binder. For example, the additives can alter or improve physical and rheological characteristics such as stiffness, effective temperature range, and low temperature properties of the asphalt binder.

[0062] Asphaltenes include extensive condensed ring systems with some level of unsaturation. The asphaltene content of typical binders can range from less than 10% to more than 20%. Asphaltenes are typically described as materials that are insoluble in n-heptane. An exact structure is unknown and based on the performance behavior of different binders it is unlikely that the asphaltene structure in any two binders is the same, especially those from different crude sources. Asphaltenes give a binder its color and stiffness and their levels in a binder tend to increase as the binder ages. Consequently, the addition of RAP or RAS or combinations of both causes the asphaltene content to increase. Increasing asphaltene content along with other products of oxidation such as carbonyls and sulfoxides are responsible for the stiffening of bituminous mixtures and their ultimate failure. By their very chemical nature asphaltenes are not readily soluble in aliphatic chemicals. Aromatic hydrocarbons will readily dissolve asphaltenes and aromatic process oils have been used in recycled mixtures. However, these oils may contain polynuclear aromatic compounds including listed potential carcinogens and therefore are not desirable additives. Most plant-based oils are straight or branched chain hydrocarbons with some level of unsaturation and therefore are not as effective at retarding aging as they are at softening the overall binders in a mixture.

[0063] Exemplary plant sterols include esters of campesterol, stigasterol, stigmasterol, P-sitosterol, A5-avenosterol, A7-stigasterol, A7-avenosterol, brassicasterol or mixtures thereof. In some embodiments, the sterol blend contains P-sitosterol as the pure sterol. In other embodiments, the sterol blend contains a mixture of pure sterol esters.

[0064] Sterol esters that are suitable for use as an anti-aging additive set out in this disclosure may include, for example, esters that are formed from a selected sterol and a selected saturated or unsaturated fatty acid. Fatty acids that are suitable may have the general formulaCH3(CH2)nCOOH, wherein n may be in the range of about 6 to 28, 8 to 28, or 10 to 28, this alkyl group may be saturated or unsaturated, and may be a straight alkyl chain or a substituted alkyl chain. Representative saturated and unsaturated fatty acids include, for example, lists of fatty acids that are available from a variety of internet sites and are well known to those skilled in the art. Representative saturated fatty acids include: Propanoic acid, Butanoic acid, Pentanoic acid, Hexanoic acid, Heptanoic acid, Octanoic acid, Nonanoic acid, Decanoic acid, Undecanoic acid, Dodecanoic acid, Tridecanoic acid, Tetradecanoic acid, Pentadecanoic acid, Hexadecanoic acid, Heptadecanoic acid, Octadecanoic acid, Nonadecanoic acid, Icosanoic acid, Heneicosanoic acid, Docosanoic acid, Tricosanoic acid, Tetracosanoic acid, Pentacosanoic acid, Hexacosanoic acid, Heptacosanoic acid, Octacosanoic acid, Nonacosanoic acid, Triacontanoic acid, and analogs to these species containing one, two, three, or more double bonds.

[0065] Exemplary crude plant sterol esters include modified or unmodified natural products containing significant quantities of sterol esters, including such diverse plant sources as com oil, wheat germ oil, sarsaparilla root, soybean pitch and com oil pitch. For example, tall oil pitch is obtained during the process of preparing paper from wood, particularly pine wood. Tall oil pitch is an extremely complex material that can contain rosins, fatty acids, oxidation products and esterified materials, an appreciable fraction of which are sterol esters. Plant sources of crude sterol esters are inexpensive in that they are the foots or tailings left from various manufacturing processes.

[0066] In some embodiments, the crude sterol ester sources include esters of stigmasterol, - sitosterol, campesterol, ergosterol, brassicasterol, cholesterol and lanosterol or mixtures thereof. In some embodiments, the crude sterol ester sources include soy bean oil, corn oil, rice bran oil, peanut oil, sunflower seed oil, safflower oil, cottonseed oil, rapeseed oil, coffee seed oil, wheat germ oil, tall oil, and wool grease. In some embodiments the crude sterol esters include a bio-derived source or partially distilled residue of the bio-derived source. In some embodiments, the crude sterol ester source includes tall oil pitch, soybean oil or com oil.

[0067] Any of the oil tailings or pitches from the disclosed plant sources is suitable crude sterol ester sources. U.S. Pat. No. 2,715,638, Aug. 16, 1955, to Albrecht, discloses a process for recovering sterol esters from tall oil pitch.

[0068] The crude sterols esters preferably are obtained from plant sources. The crude sterol esters may include components in addition to the desired sterol esters. Exemplary plant sources for crude sterols include tall oil pitch, crude tall oil, sugar cane oil, hot well skimmings, cottonseed pitch, soybean pitch, com oil pitch, wheat germ oil or rye germ oil. In some embodiments, tall oil pitch is a source of the crude sterol. Tall oil pitch can include about 30 to 40% unsaponifiable molecules. Unsaponifiables are molecules that do not react with alkali hydroxides. Fatty and rosin acidsremaining in the tall oil pitch readily react with potassium or sodium hydroxides and thus the unsaponifiables can be readily separated.

[0069] The sterol esters may be used as an anti-aging additive in an amount effective to provide a less negative ATc value after aging the asphalt binder compared to a similarly-aged binder without the anti-aging additive. In certain embodiments, the anti-aging additive can provide an asphalt binder a ATc of greater than or equal to -5.0°C. As shown herein, pure sterol (e.g. 5%) retards aging better than other additives as shown by the ATc value.

[0070] The additive added to the asphalt may for example range from about 0.5 wt.%, to about 15 wt.%, or about 1 wt.%, to about 10 wt. %, about 1 wt.% to about 3 wt.%, about 3 wt.%, to about 5 wt.%, about 5 wt.% to about 10 wt.%, about 10 wt.% to about 15 wt.%, of the virgin binder in an asphalt.

[0071] In some embodiments, the sterol ester may provide an asphalt binder with a ATc of greater than or equal to -5.0°C. In some embodiments, the sterol can provide an asphalt binder with a ATc of greater than or equal to -5.0°C after 40 hours of PAV aging. In still other embodiments, the sterol can provide an asphalt binder with a less negative ATc value and a decreased R-Value following aging, when compared to a similarly-aged asphalt binder without the sterol.

[0072] It should be noted that the terms “mixed sterol” or “sterol blends” or “sterol in blend” or grammatically equivalent phrases have been used interchangeably to refer to pure sterols.Softening Agents & Other Additives

[0073] Softening agents that may be used in binders include waste engine oil and waste engine oil that may be further processed to provide REOB. REOB is a low-cost softening additive and asphalt extender obtained from the residual material remaining after the distillation of waste engine oil either under vacuum or at atmospheric pressure conditions. The distilled fraction from the rerefining process is converted into new lubricating oil for vehicles, but the bottoms do not have an available market due to the presence of metals and other particulates from internal combustion engines. Also, these bottoms contain paraffinic hydrocarbons and additives incorporated into the original lubricating oil. For many years REOB were used by some companies as an asphalt extender, but the usage was localized.

[0074] Greater amounts of waste engine oils are being re-refined and therefore greater amounts of REOB are being sold into the asphalt binder market. The use of REOB may result in bituminous mixtures, which when aged, exhibit ATc values of -4°C or lower with consequent poor performance in pavements. When REOB are added to some asphalts at levels as low as 5% by weight, the resulting ATc after 40 hr. PAV aging can be -5°C or lower (viz., more negative). Recovered binders from field mixes shown to contain REOB by means of metals testing have shown greater distressthan field mixtures of the same age and the same aggregate and paved at the same time but not containing REOB.

[0075] The disclosed sterol can mitigate the impact of waste engine oils (e.g. REOB) on ATc (as evaluated, for example, using 40 hr. of PAV aging) and renew or retard the aging rate of the recycled asphalt.

[0076] The disclosed sterol can also be used to mitigate the impact of other softening agents, which behave similarly to REOB. In other words, the other softening agents are agents when aged, have ATc values of -4°C or lower with consequent poor performance in pavements. These other softening agents include synthetic or virgin lubricating oils (such as MOBIL™ 1 synthetic oil from ExxonMobil Corp, and HAVOLINE™ 10W40 oil from Chevron USA Inc.), virgin paraffin or naphthenic base oils, untreated or non-rerefined waste drain oils or waste engine oil materials, vacuum tower asphalt extenders (the non-distillable fraction from re-refining used engine oil) and paraffinic or naphthenic process oils.

[0077] It should be noted that softening agents such as bioderived softening agents (e.g. Cargill’s 1103 and Arizona Chemical’s RSI 100) can soften an asphalt binder without adversely affecting the asphalt binder in the same manner as REOB. The sterol can retain much of the beneficial softening of these bioderived softening agents.

[0078] The asphalt may contain other components in addition to the disclosed sterol. Such other components can include elastomers, non-bituminous binders, adhesion promoters, softening agents, rejuvenating agents, and other suitable components.

[0079] Useful elastomers include, for example, ethylene-vinyl acetate copolymers, polybutadienes, ethylene-propylene copolymers, ethylene-propylene-diene terpolymers, reactive ethylene terpolymers (e.g. ELVALOY™), butadiene-styrene block copolymers, styrene-butadiene-styrene (SBS) block terpolymers, isoprene-styrene block copolymers and styrene-isoprene-styrene (SIS) block terpolymers, chloroprene polymers (e.g., neoprenes) and the like. Cured elastomer additives may include ground tire rubber materials.

[0080] In one embodiment, the binder includes a blend of binders. In certain embodiments, the binder blend includes virgin binder and binder extracted from reclaimed asphalt. For example, the binder extracted from RAS material may be extracted from manufacturer asphalt shingle waste, from consumer asphalt shingle waste, or from a mixture of binders extracted from manufacturer and consumer asphalt shingle waste. In certain embodiments, a binder blend may include from about 60 wt % to about 95 wt % of virgin binder and from about 5 wt % to about 40 wt % of binder extracted from reclaimed asphalt such as RAS. In certain embodiments, the binder blend includes the addition of an anti-aging additive from about 0.5 wt % to about 15.0 wt % of the virgin asphalt. In certainembodiments, the binder blend can include the addition of from about 0.2 wt % to about 1 .0 wt % anti-aging additive. The anti-aging additive has been shown to improve high and low temperature properties and PG grading for both low and high temperature ends of RAS-containing asphalt binder blends.

[0081] The asphalt binder may be prepared by mixing or blending the sterol with the virgin binder to form a mixture or blend. The mixture or blend can be added to recycled asphalt materials (e.g. RAS and / or RAP) and aggregate. One of skill in the art will recognize that any sequences of adding and mixing components are possible. Asphalt can be prepared by applying mechanical or thermal convection. In one aspect, a method of preparing an asphalt involves mixing or blending a sterol with virgin asphalt at a temperature from about 100° C. to about 250° C. In some embodiments, the sterol is mixed with the virgin asphalt at a temperature from about 125° C. to about 175° C, or 180° C to 205° C. In some embodiments, the asphalt is mixed with asphalt, sterol, and softening agent. In still other embodiments, the asphalt is mixed with asphalt, RAS, RAP, or combinations of RAS and RAP, sterol, and aggregate.

[0082] The disclosed asphalt can be characterized according to ASTM specifications and test methods, in addition to many standard tests. For example, the disclosed asphalts and binders can be characterized using rheological tests (viz., dynamic shear rheometer, rotational viscosity, and bending beam).

[0083] At low temperatures (e.g., -10°C), road surfaces need cracking resistance. Under ambient conditions, stiffness and fatigue properties are important. At elevated temperature, roads need to resist rutting when the asphalt becomes too soft. Criteria have been established by the asphalt industry to identify rheological properties of a binder that correlate with likely paved road surface performance over the three common sets of temperature conditions.

[0084] To determine the ATc parameter, a 4 mm DSR test procedure as described above and developed by Western Research Institute (Sui, C., Farrar, M., Tuminello, W., Turner, T., A New Technique for Measuring low-temperature Properties of Asphalt Binders with Small Amounts of Material, Transportation Research Record: No 1681, TRB 2010. See also Sui, C., Farrar, M. J., Harnsberger, P. M., Tuminello, W.H., Turner, T. F., New Low Temperature Performance Grading Method Using 4 mm Parallel Plates on a Dynamic Shear Rheometer. TRB Preprint CD, 2011) can be used.

[0085] The ATc parameter can also be determined using the Bending Beam Rheometer (BBR) test procedure based on AASHTO T313 or ASTM D6648. It is important that when the BBR test procedure is used that the test is conducted at a sufficient number of temperatures such that results for the Stiffness failure criteria of 300 MPa and Creep or m-value failure criteria of 0.300 areobtained with one result being below the failure criteria and one result being above the failure criteria. In some instances, for binders with ATc values less than -5 °C this can require performing the BBR test at three or more test temperatures. ATc values calculated from data when the BBR criteria requirements referred to above are not met are not considered to be completely accurate.

[0086] The surface characteristics and changes can be revealed in an asphalt. These surface characteristics can be determined using atomic force microscopy (AFM). AFM is described in the following references R. M. Ovemey, E. Meyer, J. Frommer, D. Brodbeck, R. Liithi, L. Howald, H.- J. Giintherodt, M. Fujihira, H. Takano, and Y. Gotoh, “Friction Measurements on Phase-Separated Thin Films with a Modified Atomic Force Microscope”, Nature, 1992, 359, 133-135; E. zer Muhlen and H. Niehus, “Introduction to Atomic Force Microscopy and its Application to the Study of Lipid Nanoparticles”, Chapter 7 in Particle and Surface Characterization Methods, R. H. Muller and W. Mehnert Eds, Medpharm Scientific Pub, Stuttgart, 1997; H. Takano, J.R. Kenseth, S.-S. Wong, J.C. O’Brien, M.D. Porter, “Chemical and Biochemical Analysis Using Scanning Force Microscopy”, Chemical Reviews 1999, 99, 2845-2890.

[0087] Asphalt is a colloidal system in which the most important structure forming elements are the asphaltenes, which are dispersed in the maltenes. The size of the colloidal particles can be determined using different techniques: ultrafiltration, electron microscopy, small angle X-ray scattering and others. Two parameters that control the stability of asphaltene micelles are the ratio of aromatics to saturates and that of resins to asphaltenes. When these ratios decrease, asphaltene micelles will coalesce and form larger aggregates.

[0088] Asphalt samples can be fractionated into asphaltenes and maltenes using n-heptane (ASTM D3279). The asphaltenes can be precipitated while the soluble maltenes can be obtained as filtrates and subsequently fractionated by liquid chromatography into resins, aromatics, and saturated fractions. The resins can be first adsorbed and eluted from solid adsorbents followed by the recovery of the oils. The oils can be fractionated into other components: saturates, monocyclic aromatics, bicyclic aromatics and polycyclic aromatics asphaltenes, resins, aromatics and saturates, mostly called SARA, and can be determined by various methods, for example, by relying on solubility of the particular chemical groups of bitumen based on polarity. One such method that can be used to quantify three generic fractions of the maltene fraction of an asphalt can be the thin-layer chromatography-flame ionization detection (TLC-FID), also known as an latroscan procedure. The three generic fractions determined in the latroscan procedure are resins, aromatics and saturates; the asphaltenes having been determined using ASTM D3279.

[0089] As the binder ages the asphaltenes increase and generally the cyclics decrease; the saturate content does not change appreciably and the resins increase but not to the same extent at which thecyclics decrease. The overall result is that as the binder ages the Colloidal Index decreases as a result of changes to amounts of these four fractions in the binder. The reciprocal of the CI value is known as the Colloidal Instability Index (CII) and may also be used to characterize aging.

[0090] The colloidal index (CI) can be calculated from the percentage values for four fractions determined from an latroscan procedure. The calculation for CI is:

[0091] CI = (Cyclics + Resins) / (Asphaltenes + Saturates)

[0092] As the binders age the general trend is for the defect area or surface roughness to decrease. This may be interpreted to mean that initially the components that result in binder degradation are agglomerated and as they age these components oxidize resulting in chemical changes that cause the Colloidal Index to decrease. Primarily these changes appear to be an increase in asphaltenes and decrease in cyclics. These chemical changes appear to reduce the ability of the binder to relax stresses as manifested by increases in R-Value and decreases in ATc. The presence of the sterol additive appears to remove those components that cause property degradation (also referred to as deleterious components) and render them less effective than they would otherwise be. As the data shows, this retardation of degradation is not a permanent change in the binder but can substantially extend the time before the binder will reach a state of degradation were the sterol not present.

[0093] In some embodiments, the aged asphalt includes recycled asphalts, softening agents, and rejuvenating agents. For example, some asphalt includes RAS, RAP, REOB, virgin paraffinic base oils, untreated or non-rerefined waste drain oils or waste engine oil materials, vacuum tower asphalt extenders, paraffinic or naphthenic processing oils and lubricating base oils. In certain embodiments, an effective amount of an anti-aging additive can provide a less negative ATc value after aging the asphalt binder compared to a similarly-aged binder without the anti-aging additive. In some embodiments, the anti-aging additive can provide a less negative ATc value after aging an asphalt binder compared to a similarly-aged binder without the anti-aging additive. The asphalt binder can include for example at least 3% or greater RAS, at least 25% or greater RAP, at least 5% REOB or greater, at least 5% or greater paraffinic oils.

[0094] In some embodiments, the average roughness of an asphalt or binder with sterol additive is 1.5 to 350 pm2, 3.6 to 232 pm2, or 10 to 230 pm2.

[0095] The invention is further illustrated in the following non-limiting examples, in which all parts and percentages are by weight unless otherwise indicated.ExamplesExample 1

[0096] This example describes work performed with crude sterols and sterol esters produced bitumen having age retarding properties. Higher dose levels of crude sterol esters compared to puresterols were required to achieve comparable or better results. The crude sterol additive that was evaluated contained sterol esters, but the sterol ester concentration was not quantified. To definitively determine whether sterol esters can provide bitumen age retarding results an evaluation of known sterol esters was undertaken.

[0097] An online search for sterol esters produced results for sterol esters being sold commercially for the purpose of lowering cholesterol in human arteries. These sterol esters are sold as gelatin capsules containing the sterol esters in powder form. Sterol ester capsules from two such suppliers, Carlyle and HTN, were obtained. According to the labels on the containers both companies sold sterol esters comprised of beta-sitosterol, campesterol, and stigmasterol. According to the HTN label the proportion of each sterol ester was 40% beta-sitosterol, 20% campesterol, and 15% stigmasterol. This constitutes 75% (750 mg of sterol) of the mass of 1000 mg daily recommended dose. The 250 mg difference is the mass of acid used to react with the sterols to produce the esters that are in the capsules. The Carlyle label lists the same three sterols, in the same order but does not list the mass of each sterol for a serving of the supplement. The testing program followed was to remove the contents from sufficient capsules to obtain quantities of the sterol esters to be blended with the aged control bitumen for testing purposes. Due to differences in the number of capsules in each bottle of capsules the blends produced were 7.5% and 10% of the Carlyle esters by weight of the final blend and 10% of the HTN esters by weight of the final blend. These blends were PAV aged for 0, 20, 40 and 60 hours. The aged control that had been used in earlier studies was used in this investigation. Therefore, there were test results using the same aged control using 7.5% pure sterol and 7%, 10% and 13% crude sterol blends to provide comparative analysis using the same control bitumen but with different sterol containing additives.

[0098] Figure 2 shows high temperature PG Grade data at 2.2 kPa for several additives. There are additional additives shown in Figure 2 besides the Carlyle and HTN sterol esters. A blend of 7.5% sterol acetate (an ester of acetic acid). Sterol acetate reduced the initial high PG grade by 10°C, but as the aging rate, while lower than the control is significantly higher than the other additives shown in Figure 2. High temperature data for 7.5% cholestanol is similar to that for 7.5% Carlyle sterol ester and the aging slopes are 0.301 for cholestanol and 0.3085 for 7.5% Carlyle sterol ester. Cholesterol belongs to the cholestanol family; both are C27 structures but cholestanol does not have a double bond on the 6 member B ring of the structure. With this reaction point removed there is improvement in the aging rate of cholestanol compared to cholesterol. 10% HTN sterol ester (aging rate slope 0.285) has a lower aging rate than 10% Carlyle sterol ester (aging rate slope 0.317), but age at a lower rate than 13% crude sterol (aging rate slope 0.331). Although 13% crude sterol exhibits the lowest high PG Grade at 2.2 kPa at all aging conditions it does not have the best agingproperties of these additives. Crude sterol provides more softening because approximately 50% by mass of crude sterol is residual tall oil pitch which contains sterol esters as well as other tall oil molecules. Crude sterol provides a higher level of stiffness reduction as shown by high PG Grade value at zero aging time for both 10% and 13% crude sterol compared to the aging slopes for 10% HTN and Carlyle sterol ester blends.

[0099] Figure 3 shows the Tm-Critical data as a function of PAV aging level. Unlike the more dispersed high PG Grade data the Tm-Critical data are more tightly grouped. The low temperature aging rate slopes for all additives are 50% or less than that of the aged control bitumen. The range of Tm-Critical for all additives is approximately 3°C at zero aging and 4.3°C after 60-hour PAV aging. 10% HTN sterol ester had the lowest aging rate, and 13% crude sterol had the second lowest aging rate and had the lowest Tm-Critical value at zero time (28.82 °C) it also had the lowest Tm- Critical value after 60hour PAV aging. The low temperature for 13% crude sterol is, as mentioned previously, a function of the softening properties of the residual tall oil pitch content of the crude sterol. Figure 4 is a plot of asphaltene content of the additives shown in Figure 3 plus 7.5% sterol acetate. Asphaltenes increase as bitumen ages which results in increased high temperature stiffness and reduced low temperature relaxation properties and increased low temperature stiffness. We have shown the use of sterols can reduce asphaltene levels as bitumen is aged. Figure 4 shows the increase in asphaltenes of the control bitumen resulting from increased Pressure Aging Vessel aging. Figure 4 also shows that sterols and some sterol esters are able to retard the rate of asphaltene increase due to bitumen aging. The initial asphaltene levels are zero aging time are a result of dilution due to the addition of sterol additives in the original bitumen sample. For example, the addition of 7.5% pure sterol results in a dilution of asphaltenes at zero time. The asphaltene level of the control bitumen at zero time is 28.9% and multiplying 28.9% by 0.925 results in asphaltenes of 26.7%. The data label in Figure 4 shows the measured asphaltenes of the 7.5% pure sterol blend as 26.5%. The 10% HTN dose label shows asphaltene level of 24% and multiplying 28.9% by 0.9 results in asphaltenes of 26%. Asphaltenes increase as aggregates as bitumen ages and our mechanistic theory is that sterols retard the development of asphaltene aggregation. Asphaltenes of approximately 26% at zero time as shown in Figure 4 are the result of dilution and further reduction in asphaltenes are the result of dispersion by the presence of sterols. After 60-hour PAV aging the asphaltene level of the control bitumen is 34.2% and the asphaltene level of control plus 7.5% pure sterol at 60-hour PAV is 32.2%. Multiplying 34.2 by 0.925 results in an estimated asphaltene value of 31 .6%. It is important to understand that sterols will not prevent bitumen aging. The data in Figure 4 do not plot horizontal lines for asphaltene levels. Bitumen will continue to age and asphaltenes will increase. The mechanism of sterols is to slow or retard the aging of bitumen andthat is why the aging slope of sterol treated bitumen compared to the control aging slope is an important metric.

[0100] Asphaltenes are not the only parameter indicative of bitumen aging. As bitumen ages the Rheological Index (also referred to as R-Value) increases. R- Value is calculated for the data shown in Figure 5 as the log of the crossover modulus subtracted from the log of the glassy modulus which we set at a static value of 1E9 Pascals. The crossover modulus is the modulus at which the viscous modulus (G”) and the elastic modulus (G’) are equal. It is also the modulus value at which G” and G’ each have a phase angle of 45°. A review of Figure 5 shows that higher dose levels of crude sterol and sterol esters reduce the asphaltenes but also result in decreases of R-Value compared to the control at all aging levels. The slopes of all additive data aging plots, except for sterol acetate, are lower than the aging plot for the control. The lower dose levels of 7.5% pure sterol, cholestanol and Carlyle sterol esters have higher slope values than the 10% and 13% sterol esters and crude sterol blends. The substantial reduction in R-Value at zero aging time for all additive blends compared to the control shows the age retarding capability of sterols as well as the softening ability of the ester additives.Example 2

[0101] This example reports analytical work on selected asphalt samples using an latrocsan method. The latroscan procedure is Thin Layer Chromatography procedure that utilizes a Flame Ionization Detector (FID) methodology to quantify generic species in bitumen. The latroscan procedure is performed on material remaining after asphaltenes have been removed from the bitumen using normal heptane (n-heptane). The fractions quantified during the latroscan FID procedure are soluble in n-heptane; the n-heptane insoluble residue is captured on a filter and the remaining solution is captured as the filtrate and often referred to as the maltene fraction of the bitumen.

[0102] Figure 6 is an latroscan plot of a PG 64-22 bitumen prior to aging and after extended aging in the PAV for 60 hours. The inset text block identifies the asphaltenes in the unaged and the aged samples. The asphaltenes are removed from the bitumen prior to performing the latroscan procedure. Table 3 shows how the asphaltene content is used to adjust the fraction of saturates, aromatics and resins in the sample. This sample did not contain sterol. The retention values are retention times which are converted into an area under the plotted data curves. The area for each fraction is normalized so that the total area is 100%. The asphaltenes for the 60-hour PAV bitumen was 27.3% by weight. To take the asphaltenes into account for the sample the normalized area is multiplied by 0.727 which is the fraction that is not asphaltenes and calculated as follows: (100- 27.3) / l 00 which equals 72.7 / 100 or 0.727. Hence the asphaltene corrected column must total 72.7to make allowance for the 27.3% amount of asphaltenes present in the test sample. Every bitumen test that is performed must be adjusted for asphaltenes. Examination of the peak size for the unaged and the 60-hour PAV aged sample is informative. The data plotted in red is the unaged sample and blue is the 60-hour PAV sample result. As bitumen ages aromatics are converted to resins and the overlay plot shows a decrease in the aromatics and an increase in the resins area. Saturates generally show little variation unless a material is added to the bitumen that will elute with normal pentane. For these two bitumen samples the unaged sample contained 4.4% saturates asphaltene adjusted and the 60-hour PAV sample contained 3.8 % saturates asphaltene adjusted. Aromatics decreased from 57.2% to 33% and resins increased from 25.1% to 35.3%.Table 3 — latroscan results for 60-hour PAV aged bitumen.

[0103] Important information is the time region where the different fractions elute. Each fraction elutes on the latroscan rods using a solvent specific to the chemistry of the fraction. Saturates are always plotted first, aromatics second and resins third. These relative positions will be important as additional data is examined.

[0104] Figure 7 shows an latroscan plot of PG 64-22 + 12% pure sterol and the latroscan results for the blend that had been PAV aged for 60 hours prior to latroscan testing. The analyzed data for Figure 7 is shown in Table 4. The asphaltenes for the sample were 22.9% which means the adjustment factor was 0.771.Table 4 Bitumen Fraction Properties for Pure Sterol in PG 64-22 60 Hour PAV

[0105] Twelve percent pure sterol was added to the bitumen prior to aging. The asphaltene adjusted sterol content is shown as 13.3%. When the latroscan test is performed data is collected and averaged from five replicate samples. The quantification is not perfect and depends on how uniformly the different fractions were carried by the eluting solvents for any particular fraction. The most important feature of Figure 7 is the location of the sterol component relative to the main resin peak of the sample. When sterols were initially being evaluated an latroscan test was performed on the pure sterol sample without being blended in bitumen. Figure 8 is a screen capture of the result which shows a peak in the resin region and based on that result sterols were expected to show up associated with the resin fraction Figure 9 is an latroscan data plot of PG 58-28 with 10% crude sterol added by weight of the total blend. The analysis for the data is Table 5, the asphaltene amount was 11.7% and adjustment factor is 0.883. The sample was unaged; the crude sterol dose was 10% by weight and the asphaltene adjusted level is calculated as 11 .6%. The exact amount of sterol in the crude sterol sample is variable due to the processing procedure. A portion of the crude sterol additive contains residual tall oil pitch which will include sterol esters and tall oil fatty and rosin acids. Regardless of the specific composition the crude sterol fraction shows up as smaller peak region adjacent and appended to the main resin fraction. When resins are quantified the sterol portion is included in the total resin fraction. It is important to know that resins are the least reactive component in bitumen and sterols are also low in reactivity due to their molecular structure which has only a few reactive sites on the molecule.Table 5 - Fractional Components For Crude Sterol Blend Component

[0106] Because crude sterol contains some sterol esters an investigation into the potential age retarding properties of pure sterol esters was conducted. Sterol esters from commercial chemical suppliers are very expensive; an alternative was to obtain suppliers of sterol esters sold as over the counter pills to reduce the cholesterol levels in humans. Sterol esters have reduced melting points due to the acids reacted with the sterols to produce the esters. Sterol esters are also fat soluble andtherefore are more readily digestible by humans. In the body sterol esters cannot pass through the artery walls to the bloodstream where they compete with cholesterol for presence in the artery. The literature on the need for sterol esters to be hydrolyzed in the body to remove the acid moiety and leave only the sterol molecule available to pass the artery wall is relatively recent. Two papers from the University of Nebraska published in The Journal of Nutrition Biochemical, Molecular, and Genetic Mechanisms are referenced: Carden, Trevor J., Hang, Jiliang, Dussaul, Patrick H., and Carr, Timothy P. Dietary Plant Sterol Esters Must be Hydrolyzed to Reduce Intestinal Cholesterol Absorption in Hamsters, The Journal of Nutrition Biochemical, Molecular, and Genetic Mechanisms, J. Nutr 2015: 145: 1402-7 and Carr, Timothy P., Krogstrand, Kaye L. Stanek, Schlegel, Vicki L., and Fernandez, Maria Euz, Sterate-Enriched Plant Sterol Esters Lower Serum LDL Cholesterol Concentration in Normo- and Hypercholesterolemic Adults, The Journal of Nutrition Biochemical, Molecular, and Genetic Mechanisms J. Nutr. 139: 1445-1450, 2009. The significance of these papers is that if the acid functionality can be removed from the esters the resulting sterols can provide cholesterol lowering impacts to humans. The goal with respect to bitumen age retardation is not to remove the acid functionality from sterol esters but to ascertain whether sterol ester molecules given their structure can provide an age retarding benefit. Sterol esters are large molecules; there is only one point of attachment between the sterol and the acid and that is at hydroxyl group on the A ring of the sterol molecule. Conceptually there is a sterol entity and an acid entity to the ester molecule. Potentially the sterol end of the sterol ester could still provide some age retarding benefits with the bitumen. This conceptual idea was the basis for evaluating sterol esters for bitumen age retarding properties.

[0107] Investigation of sterol esters in the over-the-counter medications resulted in finding several suppliers of cholesterol lowering sterol ester pills. Two suppliers were identified, and containers of their sterol esters were purchased. The suppliers were Carlyle plant sterols and HTN sterol supplements. Both of these sources listed their sterols in the same order on their labels as betasitosterol, campesterol and stigmasterol. The HTN medication listed the composition 40% betasitosterol, 20% campesterol and 15% stigmasterol. This constituted 600 mg of a recommended serving dose of 1000 mg. The assumption was made that the remaining 400 mg was the acid used to produce the esters. The Carlyle label was less informative as to mass ratios. Because there were more Carlyle capsules the decision was made to make blends with the Carlyle capsule contents using the aged control bitumen and 7.5% and 10% of the Carlyle sterol esters and a 10% only blend of the HTN sterol esters. Figure 10 is an latroscan plot of 10% HTN sterol ester material with no aging. The plot of Figure 10 shows a sterol ester peak as initial portion of the resin peak as had been observed with the crude sterol latroscan data. The latroscan plots of Figure 11 show the HTN sterolester peaks at slightly shifted positions relative to the main ester peak. At zero, 20 and 40 hour aging the HTN sterol ester area is appended to the main resin peak, but after 60-hour PAV aging there is a slight shift towards the cyclics (aromatics) region. This is important for two reasons — data for other additives that will be reported show that as the sterol ester latroscan areas move towards the aromatics region the aging rate increases and there is an increase in the ratio of R-Value for an additive at a given PAV aging time when divided by R- Value of control bitumen at the same aging time. This increase in the ratio means that the additive is losing its ability to retard aging because with increased aging R-Value is increasing. There is an expectation that R-Value will increase as the bitumen ages but when there is a noticeable increase in R-Value at 60 hour PAV aging compared to 40 hour PAV aging there is some cause for concern. Further data will elucidate this in more detail.

[0108] Figure 12 is a plot of 10% Carlyle Sterol Ester unaged and after 60 hour PAV. There is not as much of a shift towards aromatics as is seen in Figure 11 , but the sterol ester region for 10% Carlyle has the same appearance as 10% HTN sterol ester after 40 hour PAV. This is not a drastic change for the 10% Carlyle sample but it is indicative of some degradation. As previously mentioned, the aging of bitumen cannot be prevented. The best approach is to find materials that age slowing at a reasonable expense.

[0109] Further additional non-limiting embodiments are provided below to further exemplify the present disclosure:

[0110] 1. An asphalt binder comprising virgin asphalt binder, reclaimed asphalt binder material comprising RAP, RAS or combinations of both and 0.5 to 15 wt.% of an anti-aging additive based on the virgin asphalt binder.

[0111] 2. The asphalt binder of embodiment 1, wherein the anti-aging additive is 1 wt.% to 10 wt. %, or 1 wt.% to 3 wt.% of the virgin asphalt binder.

[0112] 3. The asphalt binder of embodiment 1, wherein the anti-aging additive comprises at least one sterol ester.

[0113] 4. The asphalt binder of embodiment 3, wherein anti-aging additive comprises a blend of sterol esters.

[0114] 5. The asphalt binder of embodiment 3, wherein the anti-aging additive comprises a stanol ester.

[0115] 6. The asphalt binder of embodiment 4, wherein the sterol comprises a plant sterol ester.

[0116] 7. The asphalt binder of embodiment 5, wherein the stanol comprises a plant stanol ester.

[0117] 8. The asphalt binder of embodiment 1, further comprising a softening agent.

[0118] 9. The asphalt binder of embodiment 8, wherein the softening agent comprises a re -refined engine oil bottoms.

[0119] 10. The asphalt binder of embodiment 1, further comprising aggregate.

[0120] 11. The asphalt binder of embodiment 1, wherein the asphalt binder provides a ATc of -5.0 or greater.

[0121] 12. The asphalt binder of embodiment 1, wherein the anti-aging additive is present in an amount effective to provide a less negative ATc value after aging the asphalt binder compared to a similarly-aged binder without the anti-aging additive.

[0122] 13. A paved surface comprising the asphalt binder of embodiment 1.

[0123] 14. A method for slowing the aging or restoring aged asphalt binder comprising: adding an anti-aging additive to an asphalt binder, wherein the asphalt binder comprises a virgin asphalt binder, reclaimed asphalt binder material comprising RAP, RAS or combinations of both and 0.5 wt.% to 15 wt.% of an anti-aging additive based on the virgin asphalt binder.

[0124] 15. The method of embodiment 14, wherein the anti-aging additive is 1 wt.% to 10 wt. %, or 1 wt.% to 3 wt.% of the virgin asphalt binder.

[0125] 16. The method of embodiment 14, wherein the anti-aging additive comprises a sterol ester.

[0126] 17. The method of embodiment 16, wherein the anti-aging additive comprises a blend of sterol esters.

[0127] 18. The method of embodiment 16, wherein the anti-aging additive comprises a stanol ester.

[0128] 19. The method of embodiment 17, wherein the sterol ester comprises a plant sterol ester.

[0129] 20. The method of embodiment 18, wherein the stanol ester comprises a plant stanol ester.

[0130] 21. An asphalt binder comprising 1 to 10 wt% sterol ester and 1 to 8% wt% bio-derived or petroleum-derived oil based on total asphalt binder weight.

[0131] 22. The asphalt binder of embodiment 21, wherein the asphalt binder is a Performance Graded binder with or without polymer modification

[0132] 23. The asphalt binder of embodiment 21, wherein the asphalt binder contains 0.1 to 2 wt% polyphosphoric acid based on total asphalt binder weight.

[0133] 24. The asphalt binder of embodiment 21, wherein the asphalt binder containing the sterol and bio-derived or petroleum-derived oil is blended with recovered asphalt from tear off shingles or manufacturer's waste shingles.

[0134] 25. The asphalt binder of embodiment 24, wherein the shingles are tear off shingles.

[0135] 26. The asphalt binder of embodiment 25, wherein the shingles are from manufacturer’s waste shingles.

[0136] 27. The asphalt binder of embodiment 21, wherein the asphalt binder containing the sterol and bio-derived or petroleum-derived oil is used to produce a paving mixture containing 10 to70 wt% RAP based on weight of the paving mixture.

[0137] 28. The asphalt binder of embodiment 21, wherein the asphalt binder containing the sterol and bio derived or petroleum derived oil is used to produce a paving mixture containing 1 to 7 wt% RAS based on weight of the paving mixture.

Claims

ClaimsWe claim:

1. An asphalt binder comprising virgin asphalt binder, reclaimed asphalt binder material comprising RAP, RAS or combinations of both and 0.5 to 15 wt.% of an anti-aging additive based on the virgin asphalt binder.

2. The asphalt binder of claim 1, wherein the anti-aging additive is 1 wt.% to 10 wt. %, or 1 wt.% to 3 wt.% of the virgin asphalt binder.

3. The asphalt binder of claim 1, wherein the anti-aging additive comprises at least one sterol ester.

4. The asphalt binder of claim 3, wherein anti-aging additive comprises a blend of sterol esters.

5. The asphalt binder of claim 3, wherein the anti-aging additive comprises a stand ester.

6. The asphalt binder of claim 4, wherein the sterol comprises a plant sterol ester.

7. The asphalt binder of claim 5, wherein the stanol comprises a plant stanol ester.

8. The asphalt binder of claim 1, further comprising a softening agent.

9. The asphalt binder of claim 8, wherein the softening agent comprises a re-refined engine oil bottoms.

10. The asphalt binder of claim 1, further comprising aggregate.

11. The asphalt binder of claim 1, wherein the asphalt binder provides a ATc of -5.0 or greater.

12. The asphalt binder of claim 1, wherein the anti-aging additive is present in an amount effective to provide a less negative ATc value after aging the asphalt binder compared to a similarly-aged binder without the anti-aging additive.

13. A paved surface comprising the asphalt binder of claim 1.

14. A method for slowing the aging or restoring aged asphalt binder comprising: adding an anti-aging additive to an asphalt binder, wherein the asphalt binder comprises a virgin asphalt binder, reclaimed asphalt binder material comprising RAP, RAS or combinations of both and 0.5 wt.% to 15 wt.% of an anti-aging additive based on the virgin asphalt binder.

15. The method of claim 14, wherein the anti-aging additive is 1 wt.% to 10 wt. %, or 1 wt.% to 3 wt.% of the virgin asphalt binder.

16. The method of claim 14, wherein the anti-aging additive comprises a sterol ester.

17. The method of claim 16, wherein the anti-aging additive comprises a blend of sterol esters.

18. The method of claim 16, wherein the anti-aging additive comprises a stanol ester.

19. The method of claim 17, wherein the sterol ester comprises a plant sterol ester.

20. The method of claim 18, wherein the stanol ester comprises a plant stanol ester.

21. An asphalt binder comprising 1 to 10 wt% sterol ester and 1 to 8% wt% bio-derived or petroleum- derived oil based on total asphalt binder weight.

22. The asphalt binder of claim 21, wherein the asphalt binder is a Performance Graded binder with or without polymer modification23. The asphalt binder of claim 21, wherein the asphalt binder contains 0.1 to 2 wt% polyphosphoric acid based on total asphalt binder weight.

24. The asphalt binder of claim 21, wherein the asphalt binder containing the sterol and bio-derived or petroleum-derived oil is blended with recovered asphalt from tear off shingles or manufacturer's waste shingles.

25. The asphalt binder of claim 24, wherein the shingles are tear off shingles.

26. The asphalt binder of claim 25, wherein the shingles are from manufacturer’s waste shingles.

27. The asphalt binder of claim 21, wherein the asphalt binder containing the sterol and bio-derived or petroleum-derived oil is used to produce a paving mixture containing 10 to70 wt% RAP based on weight of the paving mixture28. The asphalt binder of claim 21, wherein the asphalt binder containing the sterol and bio derived or petroleum derived oil is used to produce a paving mixture containing 1 to 7 wt% RAS based on weight of the paving mixture.

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